1. Field of the Invention
The present invention relates to novel thermally stable block copolymers comprising (imide/amide) and (urea/siloxane) blocks.
2. Description of the Prior Art
The combination of recurring imide and/or amide and siloxane units has been employed to advantage in the preparation of polymers useful in insulating coating applications for which the coating must have excellent heat stability. U.S. Pat. No. 4,395,527, for example, describes polymers of this nature. More precisely, this '527 patent describes poly(imide/amides) containing recurring siloxane units which are the reaction product of a diamine having a diorganopolysiloxane group with a monoanhydride of a tricarboxylic acid, namely: ##STR3## where A represents a divalent diorganopolysiloxane group.
Other patents which describe thermally stable polymers comprising imide and/or amide and siloxane recurring units are U.S. Pat. No. 3,274,155, U.S. Pat. No. 3,325,450, U.S. Pat. No. 3,553,282 and U.S. Pat. No. 4,011,279. However, such prior art does not even allude to novel block copolymers which comprise both (imide/amide) and (urea/siloxane) blocks.